Thread: Letter grades are all E and F

Hi this program has a serious logical error I can't faddle out.
It all works fine when I enter a score of under 50, but anything
over this it prints E and ignores the other if statements.
I even made sure the range is correct before the value is passes to
the function.

Code:

#include <iostream>

// function prototype
char calculateGrade ( int );

// main function ///////////////////////////////////////////////////////////////
//
int main ( void )
{
   int score;
   
   std::cout << "Enter exam score ( 1 - 100 ): ";
   std::cin >> score;
   
   // validate input is within correct range
   if (( score < 1 ) || ( score > 100 ))
   {
      std::cout << "\nERROR: Invalid input, terminating..." << std::endl;
   }
   
   else
   {
      std::cout << "\nGrade attained: " << calculateGrade ( score ) << "\n";
   }
   
   std::cin.get(); // freeze console window output
	std::cin.ignore(); 	
	 
   return 0; // indicate program terminated sucessfully
}

// function to calculate and return letter grade dependant
// on value of score number passed
char calculateGrade ( int x )
{
   char grade = '/0'; // nulled for some kind of assignment
   
   if (( x == 100 ) || ( x >= 90 ))
      grade = 'A';
      
   if (( x == 89 ) || ( x >= 80 ))
      grade = 'B';
      
   if (( x == 79 ) || ( x >= 70 ))
      grade = 'C';
      
   if (( x == 69 ) || ( x >= 60 ))
      grade = 'D';
      
   if (( x == 59 ) || ( x >= 50 ))
      grade = 'E';
      
   if ( x < 50 )
      grade = 'F';
      
   return grade;
}

You really should use AND instead of OR. Ex.

Code:

if(x <=100 && x >= 90)
grade='A';

I think the use of OR might be causing conflicts with other if statements.

That worked thanks Sentral. The reason I used OR is because I need either expression to be TRUE for the assignmnet. Although seeing it, AND works the same as the >= operator ensures both conditions are TRUE. Doh! Silly mistake, although an easy one to make. Thanks again for the help.

EDIT ok, il change my logic, I just wanted to get it working ok before I made any changes to decrease the program size and maximise the logic